From 5a5c784c4f936b7f7b3eb2e4add658b13e56882d Mon Sep 17 00:00:00 2001
From: m-this <52073029+m-this@users.noreply.github.com>
Date: Tue, 7 Jul 2026 15:30:52 +0200
Subject: [PATCH] fix(frankenphp): strip Go's -mthreads so the Windows build
 survives Clang >= 20

Go passes the MinGW-only -mthreads flag to the C compiler for cgo builds
(golang/go#16932); Clang >= 20 rejects it for the MSVC target, so the final
frankenphp go build fails on current windows-latest (VS 18 / LLVM 20+).

Wrap Clang with a generated .bat that drops the -mthreads token and forwards
the rest, used only when the detected Clang refuses the flag.
---
 src/Package/Target/php/frankenphp.php | 37 +++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/src/Package/Target/php/frankenphp.php b/src/Package/Target/php/frankenphp.php
index 399943b3b..7692b860d 100644
--- a/src/Package/Target/php/frankenphp.php
+++ b/src/Package/Target/php/frankenphp.php
@@ -273,10 +273,11 @@ public function buildFrankenphpForWindows(TargetPackage $package, PackageInstall
         // Fix: prepend clang's directory to PATH and use plain executable names instead,
         // which matches FrankenPHP's official CI approach (CC=clang, CXX=clang++).
         $clang_dir = dirname($clang_info['clang']);
+        [$cc, $cxx] = $this->windowsCgoCompilers($package, $clang_info['clang']);
         $env = [
             'CGO_ENABLED' => '1',
-            'CC' => 'clang.exe',
-            'CXX' => 'clang++.exe',
+            'CC' => $cc,
+            'CXX' => $cxx,
             'PATH' => $clang_dir . ';' . getenv('PATH'),
             'CGO_CFLAGS' => clean_spaces($cgo_cflags),
             'CGO_LDFLAGS' => $cgo_ldflags,
@@ -377,6 +378,38 @@ public function smokeTestFrankenphpForWindows(PackageBuilder $builder): void
         }
     }
 
+    /**
+     * Return the [CC, CXX] cgo should use to build FrankenPHP on Windows.
+     *
+     * Go passes the MinGW-only `-mthreads` flag to the C compiler for cgo builds
+     * (golang/go#16932); Clang >= 20 rejects it for the MSVC target. When it does,
+     * wrap Clang with a tiny .bat that strips the flag before forwarding.
+     *
+     * @return array{0: string, 1: string}
+     */
+    protected function windowsCgoCompilers(TargetPackage $package, string $clang): array
+    {
+        $probe = $package->getSourceDir() . '\mthreads-probe.c';
+        file_put_contents($probe, "int main(void){return 0;}\n");
+        [$ret] = cmd()->execWithResult('"' . $clang . '" -mthreads -c ' . escapeshellarg($probe) . ' -o ' . escapeshellarg($probe . '.o'), false);
+        FileSystem::removeFileIfExists($probe);
+        FileSystem::removeFileIfExists($probe . '.o');
+        if ($ret === 0) {
+            return ['clang.exe', 'clang++.exe'];
+        }
+
+        logger()->info('Clang rejects -mthreads; wrapping it to strip the flag (golang/go#16932)');
+        $dir = dirname($clang);
+        $cc = $package->getSourceDir() . '\cc-nothreads.bat';
+        $cxx = $package->getSourceDir() . '\cxx-nothreads.bat';
+        // %*: the whole command line; the substring replace drops the -mthreads token,
+        // preserving quoting of paths that a for-loop would mangle.
+        file_put_contents($cc, "@echo off\r\nset \"a=%*\"\r\nset \"a=%a: -mthreads = %\"\r\n\"{$dir}\\clang.exe\" %a%\r\n");
+        file_put_contents($cxx, "@echo off\r\nset \"a=%*\"\r\nset \"a=%a: -mthreads = %\"\r\n\"{$dir}\\clang++.exe\" %a%\r\n");
+
+        return [$cc, $cxx];
+    }
+
     protected function getFrankenPHPVersion(TargetPackage $package): string
     {
         if ($version = getenv('FRANKENPHP_VERSION')) {